IV air bubble compensation

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Hello, I hope someone can help me with this question. I am a nursing student and it's been bothering me for a long time. What happens to air that enters the blood stream through a peripheral IV? I understand how the air can become an embolism, but my question is related to the scientific or physiologic mechanism that happens in the body that prevents complications. I have seen many air bubbles enter through PIVs and the people are fine. I just wonder, what really happens to the bubbles once in the body?

*Does the air bubble get absorbed somehow in the body? If so, how? Or, how does the body get rid of the small bubbles?

I've read in other forums that the lungs filter the bubbles but I don't understand exactly how, since I thought the blood stays separate from actual air in the alveoli. And also, the bubble would have to pass the right heart before getting to the lungs.

Those bubbles that you see in the IV tubings that enter the vein make their way to the chambers of the heart (remember that the veins carry blood heading back to the heart) where the turbulence causes them to break apart into even smaller bubbles. Those miniscule bubbles of air are too small to do any occlusion or occlusive damage in the body. They eventually get absorbed into the tissues of the body.

Now, having said that doesn't give nurses free rein to permit this to happen. Efforts should be taken to prevent air from getting into the IV line and the patient's vein. You should know the immediate first aid for a large amount of air that enters the blood stream: turn the patient onto their left side with the head of the bed elevated to trap the air bubble in the upper right atrium of the heart.

Our IV instructer (RN for MANY years) told us it takes around 25 cc's of air to cause an embolism. Small bubbles still give me the willy's, but I take great care to prime the lines and flick bubbles out.

"Small amounts of air do not produce symptoms because the air is broken up and absorbed from the circulation. Although classical teaching states that more than 5 mL/kg of air (IV) is required for significant injury (including shock and cardiac arrest), patient complications secondary to as little as 20 mL of air (the length of an unprimed IV infusion set) have been reported. Further, as little as 0.5 mL of air in the left anterior descending coronary artery has been shown to lead to ventricular fibrillation.

I was nationally certified in IV therapy at one time. I've always been a kind of nurse geek seeking out answers to questions like this. I just happened to know the answer to this one because I had thought of it before myself. It used to bother me to watch nurses nonchalantly let all kinds of air bubbles run into people's veins without a second thought. I would hang around a room waiting for these patient's to have strokes or heart attacks. Well, it never happened and I was determined to find out why, not that I wasn't thrilled for the patients and that they survived a major cataclysm! I can't remember the total amount it takes to cause a vessel to occlude and cause infarct of the surrounding tissue. I do remember that it took more than a full 1 milliliter bolus. That's a full bubble of 1-milliliter. IV tubing holds about 3-5 milliliters, so that's a lot of air. Most pumps will detect even the tiniest amount of air. Occassionally, a miniscule and undetectable bubble of air in the plastic of the IV tubing for IV pumps will set off the air detector in an IV pump. This is due to a defect in the manufacture of that one IV tubing that you just can't see with your eye. If you have an IV pump whose air detector keeps going off and you can't find an air bubble, just change the tubing.

The easiest way to get air out of IV tubing is still to use a needle, or the equivalent needleless substitute. I used to carry a few needles in my pocket for these emergencies. Uncap the needle, swab off a Y-port between the patient and the air bubble, take the tubing out of the IV pump (if it's on a pump), insert the needle, open the clamp on the IV tubing and atmospheric air will do the rest. It will pull all the IV fluid including any air bubbles down and out through the hub of the needle, so you need to have a trash can, a towel or something to shoot the works into unless you want a mess to clean up. D5W is very sticky when it dries. When the air is out, pull out the needle, readjust the IV flow clamp and/or put the tubing back into the IV pump and the IV will resume infusing--air bubbles will be gone.

of course, you cannot use daytonite's method when you are running chemo through an IV line....you can either pull the air out into a syringe, or push the air back up into the bag with compatible fluid (NS or D5W, depending on the chemo).